It’s a phrase you’ve likely heard – especially when someone complains about bloating after milk. But does it hold truth?
Most of us are not naturally intolerant to dairy – but our ability to digest lactose can change over time, says Amanda Avery, an expert in nutrition and dietetics at the University of Nottingham. That’s the sugar in milk, cheese, and yogurt that needs the enzyme lactase to break down properly.
We’re born with plenty of lactase, but levels often decline as our diets diversify and we consume less dairy. This means some people from regions with little dairy in their traditional diet may lose this enzyme earlier – and experience symptoms like bloating or diarrhoea when they do consume lactose.
Avery emphasises that many people experience “transient lactose intolerance”, triggered by gut disruptions such as stress or antibiotics. That discomfort can come even without a lifelong intolerance.
In many cases, if you cut out dairy and later reintroduce it, your body may need time to ramp lactase production back up – causing temporary symptoms that don’t necessarily mean permanent intolerance.
If you’re mildly sensitive – or trying to avoid becoming so – Avery recommends keeping some lactose in your diet. Small amounts of low-lactose dairy, such as hard cheeses or yogurt, can help your small intestine maintain lactase levels. Even a splash of milk in tea can support your enzyme activity.
Globally, lactose intolerance rates vary dramatically: up to 80 % of adults may experience decreased lactose tolerance with age, especially outside Northern Europe. Many cultures historically had low dairy intake and adapted by fermenting milk into cheese or yogurt – which reduces lactose naturally.
Are we all a little intolerant to dairy?
No – but many of us can become temporarily sensitive to lactose due to aging, changes in diet, or gut disturbance.
Most people aren’t permanently intolerant, and mild, regular dairy exposure (like yogurt or cheese) can help maintain your lactase enzyme. A varied, balanced diet is still your best defense against dairy discomfort.
